Each pouch is tested for compatibility without a case on the phone. Because they are made to fit multiple models of phones the fit each phone differently, a tight fit versus a looser fit.
If you have a protective cover on your phone please only look at the Oversized, Extended and XXL Pouches. Oversized pouches that are made to fit the phone with a standard case. If you have a heavy duty cover on your phone we recommend you measure your phone and compare your dimensions to the ones listed in the product description to guarantee the phone will fit.